Polystichum uahukaense
| Polystichum uahukaense | ||||||||||||
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Polystichum uahukaense |
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| Scientific name | ||||||||||||
| Polystichum uahukaense | ||||||||||||
| Lorence & WLWagner |
Polystichum uahukaense is a plant from the genus of polystichum ( polystichum ) within the family of dryopteridaceae (Dryopteridaceae). It is only known from the type location on the island of Ua Huka , which is one of the Marquesas Islands in the South Pacific .
description
Polystichum uahukaense grows as a fern . It forms an upright or semi-upright, 3 to 4 centimeter long rhizome , which is covered with scales and has a diameter of 1.5 to 3 centimeters. The uniformly brown to dark brown scales on the rhizome are linear-oblong with a length of 2 to 2.8 centimeters and a width of 0.2 to 0.25 centimeters and have entire or irregularly toothed scale edges.
On each rhizome there are five to seven fronds arranged like tufts . The fronds have 16 to 43 centimeters long stems. They are furrowed on the top and densely covered with brown scales at the base, which resemble those of the rhizome and are linear to linear-oblong with a length of 1 to 2 centimeters and a width of 0.1 to 0.2 centimeters. The scales have thin serrated edges. In addition, the stems are covered with hair-like scales. The density of the scales decreases towards the tip of the frond stem, but these can also be completely absent.
The double-pinnate fronds are elongated-ovoid to almost oblong with a length of 26 to 58 centimeters and a width of 12 to 27 centimeters and consist of 20 to 30 pairs of leaflets. The main axis of the fronds is densely covered with pale brown, hair-like scales, which are 0.3 to 0.6 inches long. The more or less paper-like leaflets are almost oppositely arranged on the frond stalks and can have small auricles . The bottom one or two pairs of leaflets have receded somewhat. The leaflets consist of 8 to 16 pairs of leaflets , which are the same size on the downward-facing side of the leaflets as on the upward-facing side. The largest leaflets are elongated with a length of 6 to 15 centimeters and a width of 1.5 to 3 centimeters. The leaflets have a pointed or blunt tip, can be deeply incised and form an almost free-standing, obovate lobe. The upper side of the young leaflets is sparsely covered with glandular hairs, which, however, disappear with increasing age. Even with older leaflets, the underside is covered with light brown hair scales on the leaf veins , the leaf veins and the edges. The leaflet margins are notched. The branching leaf veining is difficult on the upper side of the leaflet, but clearly recognizable on the lower side.
The thin, light brown Sori are mostly short-lived and are covered by a shield-shaped indusium , which is 0.5 to 0.6 millimeters in size. The spores are black.
Occurrence
Polystichum uahukaense is endemic to the island of Ua Huka , one of the Marquesas Islands in the southern Pacific . Polystichum uahukaense has so far only been found on a rock wall at the top of a valley near the villages of Hane and Hokatu at an altitude of about 520 meters. This damp rock face overgrown with moss lies in the shadow of a damp forest in which the linden-leaved marshmallow ( Hibiscus tiliaceus ) and Pandanus tectorius grow. Bidens polycephala , Boehmeria virgata , Dryopteris macropholis , Macropiper latifolium , Microsorum grossum , sword fern species ( Nephrolepis spec.), Peperomia pallida , Phyllanthus pacificus , Pteris comans , Selaginella arbuscula and Tectaria jardinii also grow as socialized species on the rock face.
Systematics
It was first described as Polystichum uahukaense in 2011 by David H. Lorence and Warren Lambert Wagner in PhytoKeys , number 4, page 25. The specific epithet uahukaense refers to the island of Ua Huka , on which this species is endemic.
The closest related species is Polystichum rapense , which is native to the island of Rapa Iti .
swell
- David H. Lorence, Warren L. Wagner, Kenneth R. Wood, Alan R. Smith: New pteridophyte species and combinations from the Marquesas Islands, French Polynesia . In: PhytoKeys . No. 4 , 2011, ISSN 1314-2003 , p. 5-51 , doi : 10.3897 / phytokeys.4.1602 .
Individual evidence
- ↑ a b c d e f g h David H. Lorence, Warren L. Wagner, Kenneth R. Wood, Alan R. Smith: New pteridophyte species and combinations from the Marquesas Islands, French Polynesia . In: PhytoKeys . No. 4 , 2011, ISSN 1314-2003 , p. 5-51 , doi : 10.3897 / phytokeys.4.1602 .
- ↑ Polystichum uahukaense. In: The International Plant Names Index. www.ipni.org, accessed on March 22, 2015 (English).
